The present invention is directed to aqueous ink compositions. More specifically, the present invention is directed to aqueous ink compositions particularly suitable for use in ink jet printing processes. One embodiment of the present invention is directed to an ink composition which comprises water, a colorant, and a compound of the formula ##STR2## wherein A.sup.1, A.sup.2, A.sup.3, B.sup.1, B.sup.2, and B.sup.3 each, independently of each other, are linear alkenyl groups, A.sup.1, A.sup.2, A.sup.3, B.sup.1, B.sup.2, and B.sup.3 each, independently of each other, are either unsubstituted or substituted with alkyl groups, m, n, and p each, independently of each other, are integers of from 0 to about 10, and R.sup.1, R.sup.2, and R.sup.3 each, independently of each other, are hydrogen, alkyl groups, cycloalkyl groups, phenyl groups, or alkylphenyl groups.
Ink jet printing systems generally are of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through at least one orifice or nozzle. The stream is perturbed, causing it to break up into droplets at a fixed distance from the orifice. At the break-up point, the droplets are charged in accordance with digital data signals and passed through an electrostatic field which adjusts the trajectory of each droplet in order to direct it to a gutter for recirculation or a specific location on a recording medium. In drop-on-demand systems, a droplet is expelled from an orifice directly to a position on a recording medium in accordance with digital data signals. A droplet is not formed or expelled unless it is to be placed on the recording medium.
Since drop-on-demand systems require no ink recovery, charging, or deflection, the system is much simpler than the continuous stream type. There are two types of drop-on-demand ink jet systems. One type of drop-on-demand system has as its major components an ink filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses. The relatively large size of the transducer prevents close spacing of the nozzles, and physical limitations of the transducer result in low ink drop velocity. Low drop velocity seriously diminishes tolerances for drop velocity variation and directionality, thus impacting the system's ability to produce high quality copies. Drop-on-demand systems which use piezoelectric devices to expel the droplets also suffer the disadvantage of a slow printing speed.
The other type of drop-on-demand system is known as thermal ink jet, or bubble jet, and produces high velocity droplets and allows very close spacing of nozzles. The major components of this type of drop-on-demand system are an ink filled channel having a nozzle on one end and a heat generating resistor near the nozzle. Printing signals representing digital information originate an electric current pulse in a resistive layer within each ink passageway near the orifice or nozzle, causing the ink in the immediate vicinity to evaporate almost instantaneously and create a bubble. The ink at the orifice is forced out as a propelled droplet as the bubble expands. When the hydrodynamic motion of the ink stops, the process is ready to start all over again. With the introduction of a droplet ejection system based upon thermally generated bubbles, commonly referred to as the "bubble jet" system, the drop-on-demand ink jet printers provide simpler, lower cost devices than their continuous stream counterparts, and yet have substantially the same high speed printing capability.
The operating sequence of the bubble jet system begins with a current pulse through the resistive layer in the ink filled channel, the resistive layer being in close proximity to the orifice or nozzle for that channel. Heat is transferred from the resistor to the ink. The ink becomes superheated far above its normal boiling point, and for water based ink, finally reaches the critical temperature for bubble formation or nucleation of around 280.degree. C. Once nucleated, the bubble or water vapor thermally isolates the ink from the heater and no further heat can be applied to the ink. This bubble expands until all the heat stored in the ink in excess of the normal boiling point diffuses away or is used to convert liquid to vapor, which removes heat due to heat of vaporization. The expansion of the bubble forces a droplet of ink out of the nozzle, and once the excess heat is removed, the bubble collapses on the resistor. At this point, the resistor is no longer being heated because the current pulse has passed and, concurrently with the bubble collapse, the droplet is propelled at a high rate of speed in a direction towards a recording medium. The resistive layer encounters a severe cavitational force by the collapse of the bubble, which tends to erode it. Subsequently, the ink channel refills by capillary action. This entire bubble formation and collapse sequence occurs in about 10 microseconds. The channel can be retired after 100 to 500 microseconds minimum dwell time to enable the channel to be refilled and to enable the dynamic refilling factors to become somewhat dampened. Thermal ink jet processes are well known and are described in, for example, U.S. Pat. Nos. 4,601,777, 4,251,824, 4,410,899, 4,412,224, and 4,532,530, the disclosures of each of which are totally incorporated herein by reference.
U.S. Pat. No. 4,314,086 (Soula et al.), the disclosure of which is totally incorporated herein by reference, discloses aliphatic/aromatic ethers prepared by reacting an aliphatic halide with either an alkali or alkaline earth metal, or ammonium phenolate or naphtholate, in an inert organic solvent, and in the presence of at least one tertiary amine sequestering agent having the formula N[CHR.sub.1 CHR.sub.2 --O--CHR.sub.3 --(CHR.sub.4 --O--).sub.n R.sub.5 ].sub.3.
U.S. Pat. No. 4,417,048 (Soula et al.), the disclosure of which is totally incorporated herein by reference, discloses organonitrogen compounds bearing a labile hydrogen atom directly bonded to a reactive nitrogen function, e.g., nitrogen heterocycles or substituted anilines, which are N-alkylated with an N-alkylating agent in the presence of inorganic base and at least one sequestering agent having the structural formula N[[CHR.sub.1 CHR.sub.2 --O--CHR.sub.3 --(CHR.sub.4 --O--).sub.n R.sub.5 ].sub.3, wherein n is a number ranging from 0 to 10, R.sub.1, R.sub.2, R.sub.3, and R.sub.4, which may be identical or different, each represent a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms, and R.sub.5 represents an alkyl or cycloalkyl radical having 1 to 12 carbon atoms, a phenyl radical, or a radical of the formula --C.sub.m H.sub.2m --.PHI. or C.sub.m H.sub.2m+1 --.PHI.--, m ranging from 1 to about 12 and .PHI. being phenyl.
U.S. Pat. No. 4,408,075 (Soula et al.), the disclosure of which is totally incorporated herein by reference, discloses a process of preparing tris-(ether-amines) of the formula N[A--O--(B--O).sub.n --R].sub.3 in which R represents a hydrocarbon radical, A and B represent alkanediyl radicals, and n is a whole number between zero and 4, by ammonolysis of an alkylene glycol mono-ether of the formula HO--A--O--(B--O).sub.n --R in the presence of 10 to 40 percent by weight of a hydrogenation-dehydrogenation catalyst, based on weight of said alkylene glycol monoether.
U.S. Pat. No. 4,560,814 (Soula), the disclosure of which is totally incorporated herein by reference, discloses a process for alkylating halogenated and trifluoromethylated benzene compounds. An alkyl halide is reacted with a benzene compound having two or three substituents selected from the group consisting of the halogens and the trifluoromethyl group, and also having a hydrogen atom whose two ortho positions are occupied by two of the said substituents. The reaction is carried out in the presence of at least one alkali metal amide and at least one agent that complexes with the cation of the alkali metal amide.
U.S. Pat. No. 4,348,520 (Bruls et al.), the disclosure of which is totally incorporated herein by reference, discloses an improved method for the preparation of melamine by the conversion of urea and/or thermal decomposition products thereof. The urea and/or thermal decomposition products are converted to melamine in the presence of a gas mixture containing ammonia and carbon dioxide in a reaction zone containing a fluidized bed of catalytically active material. Melamine is desublimated from the melamine containing gas mixture in a desublimation zone by a dry-capture method leaving a desublimator off-gas mixture of ammonia, carbon dioxide, and gaseous impurities. A major portion of this desublimator off-gas mixture is compressed and recirculated to the reaction zone as a fluidizing gas for the bed of catalytically active material, without intervening treatment to remove gaseous impurities from the desublimator off-gas.
While known compositions and processes are suitable for their intended purposes, a need remains for ink compositions suitable for thermal ink jet printing. In addition, there is a need for aqueous ink compositions which enable the use of dyes which exhibit low solubility in water. Further, there is a need for ink compositions which, when employed in thermal ink jet printing processes, exhibit reduced kogation. Additionally, there is a need for ink compositions in which the effect of any monovalent or divalent cations present in the ink is minimized.